As devices for wireless audio communication, a so-called radio transceiver (terminal device) for transmitting a high-frequency carrier which is a continuous time signal by modulating it with an analog signal or a digital signal has been on a mainstream. The radio transceiver basically performs one-to-one communication, but those having a group communication function for communicating among a plurality of the radio transceivers have been proposed.
The applicant has proposed full-duplex group communication using a relaying device in previous applications such as Japanese Patent Laid-Open No. 2014-087027 (non-disclosed at the date of basic application), for example.